“Just because someone show a case where indexes do not need to be rebuilt, that DOES NOT mean that positive cases don’t exist!

I can write a test case to ‘prove’ that virtually any statement about Oracle is un-true. It’s easy.

People who believe that a single negative test case proves something is wrong join the ranks of the ‘deniers’, folks who cite ‘proof’ that the moon landing never happened, and that 911 was a government conspiracy.”

“100% true? You are joking, right? There is NOTHING that is 100% true about database tuning . . . . YOU CANNOT PROVE ANYTHING ABOUT ORACLE PERFORMANCE. EVER. NO EQUATIONS, NO PROOFS, NO WAY, NO HOW. . . . Only fools or charlatans will claim that something about Oracle performance has been ‘proven wrong’. . . .

“It’s ridiculous to reverse engineer Oracle with test cases, when we can ask the people who hold the source code.”

“A test case is not the same as software testing!

The problem is that a single-user ‘test case’ on a PC is not a valid test, by any measure. . .

It does not accurately reproduce real-world behavior, especially in performance tuning, where slowdowns are only seen under heavy loads.”

“It baffles me why any practicng DBA would want to write a test case, when they have a real-world test database, full of real data and waiting to be used . . .”

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(Added February 24, 2010):

If you search this site for the phrase test case, I think that it will be clear that test cases, when properly constructed, are extremely helpful for determining how things work – and how things should not work. Properly constructing a test case is critical to help eliminate false causation and false correlation. Employing the scientific method (secondary reference) is important when building test cases to help control false positives and false negatives. Keep in mind that if something is stated as an absolute (for example “the sun rises in the East” or “on Earth the sun always rises from the East“), it only requires a single negative test case to refute the absolute statement.

Hints for Posting Code Sections in Comments

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When the spacing of text in a comment section is important for readability (execution plans, PL/SQL blocks, SQL, SQL*Plus output, etc.) please use a <pre> tag before the code section and a </pre> tag after the code section:

<pre>

SQL> SELECT
2 SYSDATE TODAY
3 FROM
4 DUAL;
TODAY
---------
01-MAR-12

</pre>
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When posting test case samples, it is much easier for people to reproduce the test case when the SQL*Plus line prefixes are not included - if possible, please remove those line prefixes. This:

SELECT
SYSDATE TODAY
FROM
DUAL;

Is easier to execute in a test case script than this:

SQL> SELECT
2 SYSDATE TODAY
3 FROM
4 DUAL;

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Greater than and Less than signs in code sections are often interpretted as HTML formatting commands. Please replace these characters in the code sections with the HTML equivalents for these characters: